var Encoder = {
    // private property
    _keyStr: "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=",

    // public method for encoding
    Encode64: function (input) {
        var output = "";
        var chr1, chr2, chr3, enc1, enc2, enc3, enc4;
        var i = 0;

        input = Encoder._utf8_encode(input);

        while (i < input.length) {

            chr1 = input.charCodeAt(i++);
            chr2 = input.charCodeAt(i++);
            chr3 = input.charCodeAt(i++);

            enc1 = chr1 >> 2;
            enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
            enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
            enc4 = chr3 & 63;

            if (isNaN(chr2)) {
                enc3 = enc4 = 64;
            } else if (isNaN(chr3)) {
                enc4 = 64;
            }

            output = output +
                this._keyStr.charAt(enc1) + this._keyStr.charAt(enc2) +
                    this._keyStr.charAt(enc3) + this._keyStr.charAt(enc4);

        }

        return output;
    },

    Decode64: function (input) {
        var output = "";
        var chr1, chr2, chr3;
        var enc1, enc2, enc3, enc4;
        var i = 0;

        input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");

        while (i < input.length) {

            enc1 = this._keyStr.indexOf(input.charAt(i++));
            enc2 = this._keyStr.indexOf(input.charAt(i++));
            enc3 = this._keyStr.indexOf(input.charAt(i++));
            enc4 = this._keyStr.indexOf(input.charAt(i++));

            chr1 = (enc1 << 2) | (enc2 >> 4);
            chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
            chr3 = ((enc3 & 3) << 6) | enc4;

            output = output + String.fromCharCode(chr1);

            if (enc3 != 64) {
                output = output + String.fromCharCode(chr2);
            }
            if (enc4 != 64) {
                output = output + String.fromCharCode(chr3);
            }

        }

        output = Encoder._utf8_decode(output);

        return output;

    },

    // private method for UTF-8 encoding
    _utf8_encode: function (string) {
        string = string.replace(/\r\n/g, "\n");
        var utftext = "";

        for (var n = 0; n < string.length; n++) {

            var c = string.charCodeAt(n);

            if (c < 128) {
                utftext += String.fromCharCode(c);
            } else if ((c > 127) && (c < 2048)) {
                utftext += String.fromCharCode((c >> 6) | 192);
                utftext += String.fromCharCode((c & 63) | 128);
            } else {
                utftext += String.fromCharCode((c >> 12) | 224);
                utftext += String.fromCharCode(((c >> 6) & 63) | 128);
                utftext += String.fromCharCode((c & 63) | 128);
            }

        }

        return utftext;
    },

    // private method for UTF-8 decoding
    _utf8_decode: function (utftext) {
        var string = "";
        var i = 0;
        var c = c1 = c2 = 0;

        while (i < utftext.length) {

            c = utftext.charCodeAt(i);

            if (c < 128) {
                string += String.fromCharCode(c);
                i++;
            } else if ((c > 191) && (c < 224)) {
                c2 = utftext.charCodeAt(i + 1);
                string += String.fromCharCode(((c & 31) << 6) | (c2 & 63));
                i += 2;
            } else {
                c2 = utftext.charCodeAt(i + 1);
                c3 = utftext.charCodeAt(i + 2);
                string += String.fromCharCode(((c & 15) << 12) | ((c2 & 63) << 6) | (c3 & 63));
                i += 3;
            }

        }

        return string;
    },

//    xLzwEncode: function (s) {
//        var dict = {};
//        var data = (s + "").split("");
//        var out = [];
//        var currChar;
//        var phrase = data[0];
//        var cxd = 256;
//        for (var i = 1; i < data.length; i++) {
//            currChar = data[i];
//            if (dict[phrase + currChar] != null) {
//                phrase += currChar;
//            } else {
//                out.push(phrase.length > 1 ? dict[phrase] : phrase.charCodeAt(0));
//                dict[phrase + currChar] = cxd;
//                cxd++;
//                phrase = currChar;
//            }
//        }
//        out.push(phrase.length > 1 ? dict[phrase] : phrase.charCodeAt(0));
//        for (var j = 0; j < out.length; j++) {
//            out[j] = String.fromCharCode(out[j]);
//        }
//        return out.join("");
//    },

    LzwDecode: function (s) {
        var dict = {};
        var data = (s + "").split("");
        var currChar = data[0];
        var oldPhrase = currChar;
        var out = [currChar];
        var cxd = 256;
        var phrase;
        for (var i = 1; i < data.length; i++) {
            var currCode = data[i].charCodeAt(0);
            if (currCode < 256) {
                phrase = data[i];
            } else {
                phrase = dict[currCode] ? dict[currCode] : (oldPhrase + currChar);
            }
            out.push(phrase);
            currChar = phrase.charAt(0);
            dict[cxd] = oldPhrase + currChar;
            cxd++;
            oldPhrase = phrase;
        }
        return out.join("");
    },

    LzwEncode: function (uncompressed) {
        //"use strict";
        // Build the dictionary.
        var i,
            dictionary = {},
            c,
            wc,
            w = "",
            result = [],
            dictSize = 256;
        for (i = 0; i < 256; i += 1) {
            dictionary[String.fromCharCode(i)] = i;
        }

        for (i = 0; i < uncompressed.length; i += 1) {
            c = uncompressed.charAt(i);
            wc = w + c;
            if (dictionary[wc]) {
                w = wc;
            } else {
                result.push(dictionary[w]);
                // Add wc to the dictionary.
                dictionary[wc] = dictSize++;
                w = String(c);
            }
        }

        // Output the code for w.
        if (w !== "") {
            result.push(dictionary[w]);
        }
        for (var j = 0; j < result.length; j++) {
            result[j] = String.fromCharCode(result[j]);
        }
        return result.join("");
    }

//    xLzwDecode: function (compressed) {
//        "use strict";
//        // Build the dictionary.
//        var i,
//            dictionary = [],
//            w,
//            result,
//            k,
//            entry = "",
//            dictSize = 256;
//        for (i = 0; i < 256; i += 1) {
//            dictionary[i] = String.fromCharCode(i);
//        }

//        w = String.fromCharCode(compressed[0]);
//        result = w;
//        for (i = 1; i < compressed.length; i += 1) {
//            k = compressed[i];
//            if (dictionary[k]) {
//                entry = dictionary[k];
//            } else {
//                if (k === dictSize) {
//                    entry = w + w.charAt(0);
//                } else {
//                    return null;
//                }
//            }

//            result += entry;

//            // Add w+entry[0] to the dictionary.
//            dictionary[dictSize++] = w + entry.charAt(0);

//            w = entry;
//        }
//        return result;
//    } 
};
